Enable more revive linter rules (#30608)

Noteable additions:

- `redefines-builtin-id` forbid variable names that shadow go builtins
- `empty-lines` remove unnecessary empty lines that `gofumpt` does not
remove for some reason
- `superfluous-else` eliminate more superfluous `else` branches

Rules are also sorted alphabetically and I cleaned up various parts of
`.golangci.yml`.

(cherry picked from commit 74f0c84fa4245a20ce6fb87dac1faf2aeeded2a2)

Conflicts:
	.golangci.yml
	apply the linter recommendations to Forgejo code as well

cmd/hook.go

@@ -482,7 +482,7 @@ func hookPrintResults(results []private.HookPostReceiveBranchResult) {
 			fmt.Fprintf(os.Stderr, "  %s\n", res.URL)
 		}
 		fmt.Fprintln(os.Stderr, "")
-		os.Stderr.Sync()
+		_ = os.Stderr.Sync()
 	}
 }